1. Field of the Invention
This invention is in the field of devices for securing looped ties to a form for settable casting compositions, such as concrete, so that the form can resist the weight of the concrete poured into it and prior to the pouring of the concrete to maintain opposed walls of the form properly spaced.
2. Description of the Prior Art
Forms for vertical wall concrete castings have generally been built from wood or steel or both. For many years the construction industry has erected such forms by interconnecting, or fastening together, a plurality of panels. Each such panel, in a widely used commercial embodiment, has a plywood facing with four steel rails which are welded together to form a rectangular frame. The welded steel frame is secured to the perimeter of the facing. Reinforcing steel cross members are provided between rails. Such panels are available in standard sizes of 4, 6 and 8 feet in height and with a standard width of 2 feet. Filler panels are available to make up odd lengths of walls.
The rails have a pair of contact flanges on each side of their web and the flanges are oriented outwardly from each panel so that the contact flanges provide two areas of contact when two panels are set side by side and are secured to one another in the process of erecting the walls of a form.
To connect adjacent aligned panels, connector slots are formed in the webs of the rails. These connector slots are uniformly spaced so that when two such panels are placed side by side and in proper alignment their connector slots are aligned. The panels of one wall can then be secured together by a wedge key which is inserted through a pair of opposed and aligned connector slots of the pair of rails between adjacent panels. A second identical wedge key fits into a slot in the first to secure the first wedge key in the rails and thus the adjacent pair of panels together. As panels are assembled to erect the walls of a form a looped tie is secured to the rails of adjacent pairs of panels with the ties preferably being uniformly spaced. The spacing of the ties is determined by the speed of the pour and the height of the form. To secure a tie to the panels, the rails are provided with tie notches which are also uniformly spaced in the same manner as the connector slots so that when the rails of two panels are aligned and fastened together their tie notches form tie slots. The relationship between the connector slots and tie slots of a pair of rails of connected panels is that lines through the centers of corresponding pairs of tie slots and connector slots will be substantially perpendicular to one another and intersect one another.
When a looped tie, a tie having a loop at each end, is to be connected between two pairs of panels of opposing walls of a form, a tie is inserted through the tie slots between a pair of rails of adjacent panels of one wall and a wedge key is inserted through the connector slots and the loop to fasten that end or loop of the tie to the pair of panels. The first wedge key is locked in place by a second similar wedge key driven into the slot of the first.
Similarly, the other loop of the tie is secured to the rails between a pair of panels of the opposite wall of the form.
One of the problems of the prior art associated with the use of pairs of wedge keys to secure looped ties to the rails of panels in opposing walls of a form is that large numbers of such wedge keys are needed. Since they are relatively small and are not secured together, the rate of loss of such devices is particularly high. In addition the insertion of such wedges through the connector slots and loop of a tie positioned between a pair of rails is difficult to do quickly and efficiently. Another problem with the prior art is that the loops of a looped tie are between the rails when locked in place so that the panels must be removed to break off, or break back, the ends of the tie within the concrete after it has set.